Activity Sensor Processing for Phrenic Nerve Activation Detection

Abstract

An implantable cardiac device includes a sensor for sensing patient activity and detecting phrenic nerve activation. A first filter channel attenuates first frequencies of the sensor signal to produce a first filtered output. A second filter channel attenuates second frequencies of the accelerometer signal to produce a second filtered output. Patient activity is evaluated using the first filtered output and phrenic nerve activation caused by cardiac pacing is detected using the second filtered output.

Description

RELATED APPLICATIONS[0001]This application claims the benefit of Provisional Patent Application Ser. No. 61 / 181,657, filed on May 27, 2009, to which priority is claimed pursuant to 35 U.S.C. §119(e) and which is hereby incorporated herein by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to cardiac devices and methods, and, more particularly, to characterization of phrenic nerve activation and phrenic nerve activation avoidance during cardiac electrical therapy.BACKGROUND OF THE INVENTION[0003]When functioning normally, the heart produces rhythmic contractions and is capable of pumping blood throughout the body. The heart has specialized conduction pathways in both the atria and the ventricles that enable excitation impulses (i.e. depolarizations) initiated from the sino-atrial (SA) node to be rapidly conducted throughout the myocardium. These specialized conduction pathways conduct the depolarizations from the SA node to the atrial myocardium, to the ...

AI Technical Summary

Benefits of technology

The present invention relates to an implantable medical device that can sense phrenic nerve activation and patient activity to better manage cardiac pacing. The device includes a pulse generator and an accelerometer to detect phrenic nerve activation caused by cardiac pacing. The device can also use filters to attenuate unwanted signals and evaluate patient activity and respiration. The invention provides a method for detecting phrenic nerve activation during a specific detection interval and adjusting pacing parameters accordingly. The invention can also include an impedance sensor to detect patient activity and respiration. Overall, the invention improves the accuracy of cardiac pacing and sensing for patient activity and metabolic demand.

Problems solved by technology

Without the synchronization afforded by the normally functioning specialized conduction pathways, the heart's pumping efficiency is greatly diminished.

Patients who exhibit pathology of these conduction pathways can suffer compromised cardiac output.

If a pace pulse energy is too low, the pace pulses may not reliably produce a contractile response in the heart chamber and may result in ineffective pacing that does not improve cardiac function or cardiac output.

Pacing pulses can unintentionally stimulate nerves or muscles, even if the pulse energy is not sufficient to capture cardiac tissue.

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